Guide pads are used during cutting machining in metals and other hard materials on, e.g., cutter heads of deep hole drilling tools in order to prevent wear of the cutter head and to guide the drilling tool during the drilling process and thereby maintain the cutter head along a straight axis line to create a bore hole which is straight with an as high accuracy as possible. For this purpose at least two guide pads are mounted in a respective seating on an outer periphery or envelope surface of the cutter head by means of e.g. screwing, clamping or soldering. A sliding surface of the guide pad which is facing outwards and bears against the circumferential bore hole, is normally formed with a part-circular cross section having the same or a somewhat smaller radius of curvature as the radius of the bore hole.
During the drilling process, the guide pad is exposed to high temperatures due to friction against the hole wall, which in combination with high pressure against the hole wall, makes the guide pads subject to wear and formation of cracks. In order to reduce the tendency of wear and crack formation, it is common practice to provide a cooling and lubricating fluid, which is fed through channels within the drilling tool into the bore hole. However, the cooling/lubricating fluid can often not, to a sufficient extent, reach the entire contact zone between the guide pad and the hole wall, which makes the cooling/lubricating insufficient, such that the wearing of and formation of cracks will still be considerable.
US 2013/0051944 discloses various guide pads, which in the embodiments according to FIGS. 5 to 8 are provided with multiple lubricating grooves in different patterns in the sliding surface. This will improve the cooling and lubricating of the contact zones between the guide pad and the hole wall since the cooling/lubricating fluid easier can be fed to each contact zone. However, unfortunately the lubricating grooves will also form fractural impressions or stress concentrations, which in its turn will promote the formation of cracks.